The development of the child / by Nathan Oppenheim.

  • Nathan Oppenheim
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: The development of the child / by Nathan Oppenheim. Source: Wellcome Collection.

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    an example. The external petro-squamous suture1 does not become obliterated until the end of the first year. Then for the first time the mastoid process becomes distinct. There is, naturally, a constant formation of new bone from the periosteum surrounding it; this is accomplished the more rapidly because this perios- teum, as well as that of all the body, is less stable in infants, is looser, softer, and more vascular than in adults. Thus the walls of the cavity of this bone continuously become thicker. Even here the growth is not absolutely regular, and on the average, the walls will grow from one millimetre at birth to one centimetre at nine or ten years. This new bone is fine cancellous tissue, which at puberty begins to un- dergo a process of absorption in scattered spots. Ab- sorption goes on gradually but surely until these areas are thus changed into a number of connecting air cells, eventually lined by a delicate mucous membrane. The same feature of irregularity is seen in the union of the bones of the head: while the fontanelles or inter-membranous spaces at the angles of the parietal bones normally disappear before the age of four years, nevertheless the occipital and sphenoid bones are not united at their basilar parts until the twentieth. Thus one naturally looks for a greater or less persistence of foetal conditions, which are then seen to disappear 1 The line of junction between the petrous and squamous portions of the temporal bone (in the head).